This application discloses subject matter pertaining to the disclosures in U.S. Patent Application No. 60/954,987, filed on Aug. 9, 2007, U.S. patent application Ser. No. 12/189,476, now U.S. Pat. No. 8,746,330, filed on Aug. 11, 2008, U.S. patent application Ser. No. 13/401,618, filed on Feb. 21, 2012, and U.S. Patent Application No. 61/512,379, filed on Jul. 27, 2011, each of which applications is hereby incorporated by reference in its respective entirety, for all purposes.
The innovations and related subject matter disclosed herein (collectively referred to as the “disclosure”) generally pertain to fluid heat exchange systems, and more particularly, but not exclusively, to cooling of electric pump motors, with a system configured to cool a stator of an electric pump motor being but one particular example. Some systems are described in relation to electronics cooling applications by way of example, though the disclosed innovations may be used in a variety of other applications.
Fluid heat exchangers are used to cool electronic and other devices by accepting and dissipating thermal energy therefrom. A coolant (or other working fluid) is often conveyed throughout a fluid circuit including a fluid heat exchanger and a pump. Often, the pump is driven by an electric motor, with a brushless DC (BLDC) motor being an example.
In a typical DC motor, permanent magnets are arranged around an outer periphery of a spinning armature. In such a motor, the permanent magnets are stationary and form a stator, while the armature rotates and forms a rotor. The armature forms an electromagnet when current passes through the armature, creating a magnetic field that interacts with the permanent magnets of the stator.
By contrast, in a BLDC motor, the electromagnet forms the stator and plural permanent magnets are arranged to define a rotor. FIG. 7 shows a photograph of such a BLDC stator. In that photograph, the stator core 132 defines an inner, generally cylindrical portion and a plurality of radial arms extending outwardly of the inner portion. An electrically conductive wire is coiled about each of the radially extending arms to define a corresponding plurality of windings, or coils 136. The stator core 132 can be formed of a ferrous alloy or any material forming a magnetic field as a result of an electrical current passing through the coils 136. As a current passes through the coils 136, the resulting magnetic field can interact with the magnetic field of the permanent magnets of the rotor to urge the rotor in rotation around the stator core 132.
Electrical-resistive heating occurs as electrical current passes through the coils 136, heating the coils and the stator core 132. Long-term reliability, motor efficiency, and other measures of electric-motor performance can degrade over time when a temperature of the stator (e.g., the stator core 132 and the coils 136) exceeds a selected threshold temperature.
Despite the existence of many previously proposed fluid heat exchange systems, there remains a need for heat exchange systems configured to provide improved thermal performance for the electrical motors, and in particular, the stators, used in such systems. As well, there remains a need for such systems configured for existing and developing small form factors. For example, there remains a need for low-profile heat exchange assemblies (e.g., integrated heat sink and pump assemblies) configured to provide stator cooling and having a vertical component height of about 27 mm, such as between about 24 mm to about 27.5 mm, or less.